1. Field of the Invention
This invention relates generally to a communications system, and, more particularly, to a wireless communications system.
2. Description of the Related Art
In wireless communications systems or networks, wireless devices typically move throughout the network communicating with one base station and then another, as their location and signal quality dictates. While the device is actively communicating, the network inherently “knows” the device's location, and thus, how best to communicate with it. There are, however, occasions when a device is not actively communicating with the network. At these times, the network only “knows” the location of the base station with which the device last communicated, and that the device may have moved relative to the last “known” location. When data needs to be delivered to the device, the network generally locates the device by systematically issuing paging signals from various likely base stations, and then awaiting a response from the user. Once a base station sufficiently near the “missing” device issues a paging signal, the user will respond, thereby locating the “missing” device.
Different strategies have been suggested for locating such a “missing” user. Typically, these strategies have three competing interests: 1) efficient resource allocation; 2) effectiveness at locating the device, and latency in locating the device. For example, latency may be enhanced by using a large amount of resource, such as by issuing paging signals from a large number of base stations at the same time. The more resources used, the quicker the “missing” user is likely to be located; however the use of resources may be inefficient. Alternatively, only a small group of base stations that are most likely to be near the “missing” user may issue paging signals. If the device is not in the vicinity of these base stations, then the paging attempt will not be effective. Alternatively, the search may be iteratively expanded, recruiting the next most likely group of base stations, until the “missing” user is located. This type of paging scheme is likely to be effective at locating the user using substantially less resources, but the time required is likely to be longer. Users may perceive the extended search period as reduced Quality of Service (QoS).
In some wireless systems, a registration methodology is used to give the network knowledge of the device location. Since these networks typically have many idle users, to maximize capacity of the system these registrations are engineered to occur as rarely as possible while still supporting the paging strategy. The registration strategy is inter-related with the paging strategy.
The present invention is directed to overcoming, or at least reducing, the effects of, one or more of the problems set forth above.